The widespread availability of computer networks has enabled people to access vast quantities of information. Computer networks, such as the Internet, can potentially connect a computer user to any of numerous sources of information. In this way, people can obtain information about any number of things, including products, services or events. Such information may be accessed for personal reasons or business reasons, making ready availability to such information useful through fixed computers or portable electronic devices.
A conventional approach to access information over a computer network is to use a search engine. The search engine develops an index of items conveying information that is available over a computer network in advance of a user's submitting a request for information. The items are formatted so that they convey information when requested by a computer user. The items, for example, may be files containing information or web pages that can be accessed over the computer network. When the search engine receives a query, representing a user's request for information about a topic, the search engine selects one or more items by matching items in the index to the search query and provides the items to the user.
A conventional approach to formulating a search query is to receive a text string input by a user. The text string may contain terms and operators defining relationships between the terms that characterize the items that are likely to be of interest to the user. For example, a search for information about camera accessories may include such terms as “camera,” “tripod,” “flash.” Such a query may also contain terms that can more precisely focus the query on items of interest to the user, such as brand names or model numbers. These additional terms may be included in the initial search query or may be added in a series of iterations, as the user reviews results of a query and then modifies the query based on returned results.
To improve the likelihood that items returned in response to a search query provide information of interest to a user, filtering may be employed in connection with searching. Using filtering, the query or set of results returned by a query may be automatically modified by the search engine. Filtering may be based on information previously obtained about a user submitting the search that reveals categories of interest to the user. The search engine may apply the information to weight search results towards items that contain information about categories determined to be of interest to the user.